Abstract
BACKGROUND: Whether individual cardiologist billings are associated with differences in ambulatory care management and clinical outcomes in patients with coronary artery disease (CAD) and heart failure (HF) remains poorly understood. METHODS: We conducted a population-based, retrospective cohort study of cardiologists who treat patients with CAD or HF using administrative claims data in Ontario, Canada. The primary exposure was cardiologist billing quintile. We then stratified median billing amounts into quintiles, from lowest (quintile 1) to highest billing physicians (quintile 5). RESULTS: The main outcomes of interest were cardiac diagnostic and therapeutic procedures that occurred within 365 days of the index visit. Our 2 cohorts respectively consisted of 170,959 patients with CAD seen by 1 of 423 cardiologists and 56,262 HF patients seen by 1 of 413 cardiologists. CAD patients of higher-billing cardiologists had higher rates of echocardiograms (adjusted odds ratio [aOR], 1.65; 95% confidence interval [CI], 1.39 to 1.94 for quintile 5 vs quintile 2) and stress tests (aOR, 1.50; 95% CI, 1.28-1.75) at 1 year, with a similar pattern for HF patients of echocardiogram (aOR, 1.40; 95% CI, 1.23-1.59; P < 0.001) and stress test (aOR, 1.32; 95% CI, 1.15-1.51) use. CAD patients of cardiologists in quintile 1 had a higher mortality rate (aOR, 1.16; 95% CI, 1.03-1.31), and HF patients of cardiologists in billing quintile 4 had a lower hospitalization rate at 1 year (OR, 0.94; 95% CI, 0.89-0.99; P = 0.02). CONCLUSIONS: Cardiac patients seen by the highest-billing cardiologists received more noninvasive cardiac testing compared with lower-billing cardiologists.